Running Gear and Mechanical Choices

65 Roadster Mark 3

You have to select an engine and transmission to use with this car. We’ve built cars for our racing programs using the full range of Ford small-block and big-block engines. The aftermarket is alive with parts and services related to this category. Additionally, today’s modern running gear provides reliable performance for less money.

It’s important when taking on this project to decide on an engine and transmission configuration that will deliver the power you need and is within your budget. About 75% of our customers choose to go with the entire engine/transmission/rear-end out of the Mustang donor car (5.0 or 4.6 liter V-8, T-5, T-45 or 3650 transmission, and Ford 8.8” rear end). The FFR Roadster kit was designed so that these parts literally bolt right in.

Our kit is also compatible with the 351 Windsor engine, the old 390/427 FE engines, the newer 429/460/514 crate motors from Ford, and the 4.6L SOHC and DOHC engines. We have had good experiences working with the crate motors offered by Ford Racing Performance Parts. You might notice that our car is featured in their Motorsports catalog!


Stock 302 Mustang engine from donor car (with supercharger)	Stock 302 Mustang engine from donor car (with supercharger)

Engines

The arguments for using the Mustang engines are pretty strong. In the mid 80’s an unprecedented quality and manufacturing revolution began in the American auto industry. Ford Motor Company, more than anyone else, began building cars with “Quality as Job 1”. Anyone who has owned a 1987 or later Mustang 5.0 will tell you that the engine, transmission and rear end, are virtually indestructible. The newer 4.6 liter SOHC and DOHC engines have enthusiastic support and a growing aftermarket. All the Mustang engines are easy to work on and readily available for a reasonable price.


Ford crate engine with EFI stack injection system	4.6 DOHC “Ford Cobra” engine 305 hp from a donor 98 Mustang

It’s hard to ignore the high performance and relatively low cost (plus huge aftermarket support!) of the Mustang package. The Mustang has defined performance value for the last 20 years. Additionally, the Mustang drivetrain has benefited from years of engineering refinements (C.A.F.E.) that have made the running gear lighter and more durable. The huge performance aftermarket that supports the Ford parts means that you can quickly and inexpensively obtain a wide selection of high performance goodies.

The standard FFR chassis with a stock 5.0 powerplant will outrun a Viper from 0-60 mph and run the quarter mile in about 13 seconds flat! Simply imagine driving a Mustang that weighs 1200 lbs. less and you’ll start to understand the possibilities with the Factory Five package!

Most small block powered cars handle the same. The big block cars and the 4.6 DOHC cars are a bit heavier in the nose. Surprisingly, our 460 powered factory car was only 140 lbs. heavier than a street car with the 302! Aluminum heads are good at keeping the weight down. For affordability, we think the small block donor car route is the best. If you decide to go with the big block motor, keep in mind that many other parts (bell housing, transmission, etc) need to be heavier duty to handle the power. Almost as a rule, customers who build kits with big block motors (or high performance small block crate motors) end up spending a more money.

Feature/Characteristic	Big block Ford Engines	Small block Ford engines w/donor car
Cost	$5-12K after all ancillary equipment is bought. Should be complimented by a heavier duty Tremec transmission ($1500).	$3,000 for entire car. Period. Go ahead and drive it. Cheap to fix, easy to work on, can be taken to Ford Dealer for servicing.
Performance	Great power w/400+ hp, great torque w/500+ ft. lb., the Ford 460 is not like an older FE motor. It is insane above 4,000 RPM and loves to rev!	Great Performance, lighter weight, 225-325 hp stock, can be easily modified with aftermarket bolt-ons.
Reliability/Maintenance	Without EFI you won’t just jump into the thing for an evening milk run. New EFI intakes “look” old style.	Computer controlled, simply change the plugs and oil every once in a while. Everyone’s daily driver favorite.
Aftermarket and Parts	Excellent. Crate motors available from Ford Motorsports. You won’t need to add performance parts.	Excellent aftermarket support, 5 hp filter kits to 150 hp superchargers etc. Still in production = Low $
Emissions	This is getting difficult in some states. Each state varies with inspection and registration standards, etc. Wherever you are, you must know the rules.	Available catalytic converters make this easier. Same emissions as a factory Mustang. Straight pipes are standard in the kit.
Which is better?	Great motors for the absolute purists or the guy who thinks too much horsepower is just enough. Deeper exhaust note, more authentic, but heavier and hotter.	A car you can drive. Great reliability, affordability and power. Lot’s of bang for the buck. Most people side with the small block for all-around competence.

Transmissions

The stock Mustang transmission is either a T-5, T-45 or 3650. We have run T-5’s in our race cars for years with excellent results. The Mustang transmissions are perfect for the street and for cars running up to 450 hp (remember that a 2,000 lb. car exerts much less stress on the running gear). The roadster kit is ready to accept the full line of Ford and many aftermarket transmissions. While there is plenty of room in the transmission tunnel for older set-ups, we still prefer sticking with the newer running gear for affordability and durability. If you would like to run an older top-loader or other transmission, call our engineers for assistance.

Rear Ends and Gearing

1987-2004 Mustang GT’s were equipped with a few different gear ratios. The majority of the cars have a 2.73 ratio. There were optional performance rears that used a 3.08 ratio and many cars were built with automatic transmissions and a fun 3.27 ratio. Keeping in mind that the T-5 is an overdrive transmission, you have some space to improve the gear ratio with aftermarket parts without compromising the street manners of the car. The most common gear sets used are 3.55 and 3.73. Check out our assembly manual for a huge tech section on running gear.

The Factory Five IRS uses the Ford 8.8” differential, but it is out of the 1989-97 Thunderbird Super Coupe. The T-Bird differentials came with 2.73, 3.08 and 3.27 gear ratios. Regardless of what rear-end is selected, the gear set is one of the easiest and least expensive way to increase performance.

Intake: Fuel Injection vs. Carbureted

Before building the car you have to decide whether you’ll be using fuel injection or carbureted systems. The EFI stuff on the Mustang works great. You can use either the Mustang donor wiring harness and computer (for EFI set-up cars) or an optional aftermarket harness that we can provide with the kit (replaces the EFI stuff).

If you are going to use the Ford computer/EFI stuff from the Mustang we’ll give you everything you need to make it work. The EFI kit provides a new air filter set-up for the mass air meter, an alternate drive pulley assembly to accommodate the air pump and custom length fan belt. Our assembly manual helps you figure out where to splice in the lights, signals and other electronics. Pulling a wiring harness and computer from your donor car can be tricky so we walk you through that as well.

Headers and Exhaust Parts

The kit exhaust parts are assembled and ready to bolt on, with all fasteners and gaskets. The standard kit comes with the side exhaust assembly which includes a pair of straight tubes, the dual side exhaust units, and the fasteners/gaskets needed. The side exhaust matches the look of original vintage cars. The entire assembly bolts directly onto the stock Mustang exhaust headers in front and onto rubber isolated mounts in the back.


advantages of volume are high quality AND low price. Ceramic coated 4-port side exhaust sets and tubular Hooker Headers

Optional catalytic converters are available as are 4 into 4 headers for improved performance. Aftermarket headers can be bought for 289/302/351/390/427/429/460 and the newer 4.6 liter Ford engines. They are made for us by Hooker Headers company and come coated in a high temperature near-chrome silver ceramic finish.

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